Saved Bookmarks
| 1. |
Ionisation enthalpies of Ce, Pr and Nd are higher than Th, Pa and U. Why? |
| Answer» SOLUTION :In the beginning when 5f orbitals begin to be OCCUPIED, they penetrate LESS into the inner core of electrons and so 5f-electrons are more effectively shielded from the nuclear charge than 4f-electrons in lanthanoids. Hence, outer electrons in ACTINOIDS are easily available for chemical bonding and so Th, pa and U have lower ionization ENTHALPIES. | |